Free and open source software is an umbrella term for software that is free and open source software. Free and open source software allows the user to inspect the source code and provides a high level of control of the software's functions compared to proprietary software.

According to the Free Software Foundation, "Nearly all open source software is free software. The two terms describe almost the same category of software, but they stand for views based on fundamentally different values."[6] Thus, the Open Source Initiative considers many free software licenses to also be open-source. These include the latest versions of the FSF's three main licenses: the GPL, the Lesser General Public License (LGPL), and the GNU Affero General Public License (AGPL).[7] Thus, terminology of free and open source software is intended to be neutral on these philosophical disagreements.

There are a number of related terms and abbreviations for free and open source software (FOSS or F/OSS) or free/libre and open source software (FLOSS).

Richard Stallman's Free Software Definition, adopted by the Free Software Foundation (FSF), defines free software as a matter of liberty, not price.[8] The earliest known publication of the definition of his free software idea was in the February 1986 edition[9] of the FSF's now-discontinued GNU's Bulletin publication. The canonical source for the document is in the philosophy section of the GNU Project website. As of August 2017, it is published there in 40 languages.[10]

In the 1950s through the 1980s, it was common for computer users to have the source code for all programs they used, and the permission and ability to modify it for their own use. Software, including source code, was commonly shared by individuals who used computers, often as public domain software.[17] Most companies had a business model based on hardware sales, and provided or bundled software with hardware, free of charge.[18] Organizations of users and suppliers were formed to facilitate the exchange of software; see, for example, SHARE and DECUS.

By the late 1960s, the prevailing business model around software was changing. A growing and evolving software industry was competing with the hardware manufacturer's bundled software products; rather than funding software development from hardware revenue, these new companies were selling software directly. Leased machines required software support while providing no revenue for software, and some customers able to better meet their own needs did not want the costs of software bundled with hardware product costs. In United States vs. IBM, filed 17 January 1969, the government charged that bundled software was anticompetitive.[19] While some software might always be free, there would be a growing amount of software that was for sale only. In the 1970s and early 1980s, some parts of the software industry began using technical measures (such as distributing only binary copies of computer programs) to prevent computer users from being able to use reverse engineering techniques to study and customize software they had paid for. In 1980, the copyright law was extended to computer programs in the United States[20]—previously, computer programs could be considered ideas, procedures, methods, systems, and processes, which are not copyrightable.[21][22]

Early on, closed-source software was uncommon until the mid-1970s to the 1980s, when IBM implemented in 1983 a "object code only" policy, no longer distributing source code.[23][24][25]

Netscape's act prompted Raymond and others to look into how to bring the FSF's free software ideas and perceived benefits to the commercial software industry. They concluded that FSF's social activism was not appealing to companies like Netscape, and looked for a way to rebrand the free software movement to emphasize the business potential of sharing and collaborating on software source code. The new name they chose was "open source", and quickly Bruce Perens, publisher Tim O'Reilly, Linus Torvalds, and others signed on to the rebranding. The Open Source Initiative was founded in February 1998 to encourage the use of the new term and evangelize open-source principles.[28]

While the Open Source Initiative sought to encourage the use of the new term and evangelize the principles it adhered to, commercial software vendors found themselves increasingly threatened by the concept of freely distributed software and universal access to an application's source code. A Microsoft executive publicly stated in 2001 that "open source is an intellectual property destroyer. I can't imagine something that could be worse than this for the software business and the intellectual-property business."[29] This view perfectly summarizes the initial response to FOSS by some software corporations.[citation needed] However, while FOSS has historically played a role outside of the mainstream of private software development, companies as large as Microsoft have begun to develop official open-source presences on the Internet. IBM, Oracle, Google and State Farm are just a few of the companies with a serious public stake in today's competitive open-source market. There has been a significant shift in the corporate philosophy concerning the development of free and open-source software (FOSS).[30]

Manufacturers of proprietary, closed-source software are sometimes pressured to building in backdoors or other covert, undesired features into their software.[31][32][33][34] Instead of having to trust software vendors users of FOSS can inspect and verify the source code themselves and can put trust on a community of volunteers and users.[35] As proprietary code is typically hidden from public view, only the vendors themselves and hackers may be aware of any vulnerabilities in them[35] while FOSS involves as many people as possible for exposing bugs quickly.[36][37]

Users of FOSS benefit from the freedoms to making unrestricted use, study, copy, modify, and redistribute such software. If they would like to change the functionality of software they can bring about changes to the code and, if they wish, distribute such modified versions of the software or often − depending on the software's decision making model and its other users − even push or request such changes to be made via updates to the original software.[38][39][40][41][35]

FOSS allows for better collaboration among various parties and individuals with the goal of developing the most efficient software for its users or use-cases while proprietary software is typically meant to generate profits. Furthermore, in many cases more organizations and individuals contribute to such projects than to proprietary software.[35] It has been shown that technical superiority is typically the primary reason why companies choose open source software.[35] Companies might build in artificial barriers, inefficiencies or undesired functionality to increase monetary return.

According to Linus's Law the more people who can see and test a set of code, the more likely any flaws will be caught and fixed quickly. However, this does not guarantee a high level of participation. Having a grouping of full-time professionals behind a commercial product can in some cases be superior to FOSS.[35][36][42] There also can be undesired functionality built intentionally into FOSS which does not get detected or fixed − e.g. due to no or few users checking the source code, changes to the software getting denied or the source code being hardly readable.

Furthermore, publicized source code might make it easier for hackers to find vulnerabilities in it and write exploits. This however assumes that such malicious hackers are more effective than white hat hackers which responsibly disclose or help fix the vulnerabilities, that no code leaks or exfiltrations occur and that reverse engineering of proprietary code is a hindrance of significance for malicious hackers.[36]

In general, it can be found that FOSS is more secure and has good user-support with some exceptions of specific − especially niche or obsolete − software solutions.

Often FOSS is not compatible with proprietary hardware or specific software. This is often due to manufacturers obstructing FOSS such as by not disclosing the interfaces or other specifications needed for members of the FOSS movement to write drivers for their hardware − for instance as they wish customers to run only their own proprietary software or as they might benefit from partnerships.[43][44][45][46][47][48][49][additional citation(s) needed]

While FOSS can be superior to proprietary equivalents in terms of software features and stability, in many cases FOSS has more unfixed bugs and missing features when compared to similar commercial software.[50][additional citation(s) needed] This varies per case and usually depends on the level of interest and participation in a FOSS project. Furthermore, unlike with typical commercial software missing features and bugfixes can be implemented by any party that has the relevant motivation, time and skill to do so.[42][additional citation(s) needed]

There is often less certainty in FOSS projects gaining the required resources / participation for continued development than commercial software backed by companies.[51][additional citation(s) needed] However companies also often abolish projects for being unprofitable and often large companies rely on and hence co-develop open source software.[37]

GNU/Linux may require more effort or technical knowledge to set up and maintain.[52] As many GNU/Linux users make extensive use of the command-line many applications lack user-friendliness such as a GUI.

In March 2009, the French Gendarmerie Nationale announced it will totally switch to Ubuntu by 2015. The Gendarmerie began its transition to open source software in 2005 when it replaced Microsoft Office with OpenOffice.org across the entire organization.[57] In September 2012, the French Prime Minister laid down a set of action-oriented recommendations about using open-source in the French public administration.[58] These recommendations are published in a document based on the works of an inter-ministerial group of experts.[59] This document stops some orientations like establishing an actual convergence on open-source stubs, activating a network of expertise about converging stubs, improving the support of open-source software, contributing to selected stubs, following the big communities, spreading alternatives to the main commercial solutions, tracing the use of open-source and its effects, developing the culture of use of the open-source licenses in the developments of public information systems. One of the aim of this experts groups is also to establish lists of recommended open-source software to use in the French public administration.[60]

In the German City of Munich, conversion of 15,000 PCs and laptops from Microsoft Windows-based operating systems to a Debian-based Linux environment called LiMux spanned the ten years of 2003 to 2013. After successful completion of the project, more than 80% of all computers were running Linux.[61] On November 13, 2017 The Register reported that Munich is planning to revert to Windows 10 by 2020.[62]

The Government of Kerala, India, announced its official support for free/open-source software in its State IT Policy of 2001,[63][discuss] which was formulated after the first-ever free software conference in India, Freedom First!, held in July 2001 in Trivandrum, the capital of Kerala. In 2009, Government of Kerala started the International Centre for Free and Open Source Software (ICFOSS).[64] In March 2015 the Indian government announced a policy on adoption of open source software.[65][66]

The Italian military is transitioning to LibreOffice and the Open Document Format (ODF). The Ministry of Defence will over the next year-and-a-half install this suite of office productivity tools on some 150,000 PC workstations - making it Europe’s second largest LibreOffice implementation. The switch was announced on September 15, 2015, by the LibreItalia Association.[67] By June 23, 2016, 6 thousand stations have been migrated.[68] E-learning military platform.[69]

In January 2010, the Government of Jordan announced a partnership with Ingres Corporation (now named Actian), an open source database management company based in the United States, to promote open-source software use, starting with university systems in Jordan.[70]

In 2005 the Government of Peru voted to adopt open source across all its bodies.[73] The 2002 response to Microsoft's critique is available online. In the preamble to the bill, the Peruvian government stressed that the choice was made to ensure that key pillars of democracy were safeguarded: "The basic principles which inspire the Bill are linked to the basic guarantees of a state of law."[74]

In September 2014, the Uganda National Information Technology Authority (NITA-U) announced a call for feedback on an Open Source Strategy & Policy[75] at a workshop in conjunction with the ICT Association of Uganda (ICTAU).

In February 2009, the United StatesWhite House moved its website to Linux servers using Drupal for content management.[76] In August 2016, the United States government announced a new federal source code policy which mandates that at least 20% of custom source code developed by or for any agency of the federal government be released as open-source software (OSS).[77] In addition, the policy requires that all source code be shared between agencies. The public release is under a three-year pilot program and agencies are obliged to collect data on this pilot to gauge its performance. The overall policy aims to reduce duplication, avoid vendor 'lock-in', and stimulate collaborative development. A new website code.gov provides "an online collection of tools, best practices, and schemas to help agencies implement this policy", the policy announcement stated. It also provides the "primary discoverability portal for custom-developed software intended both for Government-wide reuse and for release as OSS".[77] As yet unspecified OSS licenses will be added to the code.[78]

In 2004, a law in Venezuela (Decree 3390) went into effect, mandating a two-year transition to open source in all public agencies. As of June 2009[update], the transition was still under way.[79][80][needs update]

Adoption by supranational unions and international organizations[edit]

"We migrated key functions from Windows to Linux because we needed an operating system that was stable and reliable -- one that would give us in-house control. So if we needed to patch, adjust, or adapt, we could."

While copyright is the primary legal mechanism that FOSS authors use to ensure license compliance for their software, other mechanisms such as legislation, patents, and trademarks have implications as well. In response to legal issues with patents and the Digital Millennium Copyright Act (DMCA), the Free Software Foundation released version 3 of its GNU Public License in 2007 that explicitly addressed the DMCA and patent rights.

Apple, a user of GCC and a heavy user of both DRM and patents, switched the compiler in its Xcode IDE from GCC to Clang, which is another FOSS compiler[92] but is under a permissive license.[93]LWN speculated that Apple was motivated partly by a desire to avoid GPLv3.[92] The Samba project also switched to GPLv3, so Apple replaced Samba in their software suite by a closed-source, proprietary software alternative.[94]

Leemhuis criticizes the prioritization of skilled developers who − instead of fixing issues in popular applications and desktop environments − create new, mostly redundant software to gain fame and fortune.[95]

He also criticizes notebook manufacturers for optimizing their own products only privately or creating workarounds instead of helping fix the actual causes of the many issues with GNU/Linux on notebooks such as the unnecessary power consumption.[95]

Oracle in turn purchased Sun in January, 2010, acquiring their copyrights, patents, and trademarks. Thus, Oracle became the owner of both the most popular proprietary database and the most popular open-source database. Oracle's attempts to commercialize the open-source MySQL database have raised concerns in the FOSS community.[97] Partly in response to uncertainty about the future of MySQL, the FOSS community forked the project into new database systems outside of Oracle's control. These include MariaDB, Percona, and Drizzle.[98] All of these have distinct names; they are distinct projects and can not use the trademarked name MySQL.[99]

In August, 2010, Oracle sued Google, claiming that its use of Java in Android infringed on Oracle's copyrights and patents. The Oracle v. Google case ended in May 2012, with the finding that Google did not infringe on Oracle's patents, and the trial judge ruled that the structure of the Java APIs used by Google was not copyrightable. The jury found that Google infringed a small number of copied files, but the parties stipulated that Google would pay no damages.[100] Oracle appealed to the Federal Circuit, and Google filed a cross-appeal on the literal copying claim.[101] Oracle won the appeal, but Google won a subsequent retrial in 2016.[citation needed]

According to Yochai Benkler, Jack N. and Lillian R. Berkman Professor for Entrepreneurial Legal Studies at Harvard Law School, free software is the most visible part of a new economy of commons-based peer production of information, knowledge, and culture. As examples, he cites a variety of FOSS projects, including both free software and open-source.[103]

^FOSS is an inclusive term that covers both free software and open-source software, which despite describing similar development models, have differing cultures and philosophies.[1]Free refers to the users' freedom to copy and re-use the software. The Free Software Foundation, an organization that advocates the free software model, suggests that to understand the concept, one should "think of free as in free speech, not as in free beer". (See "The Free Software Definition". GNU.org. Retrieved 4 February 2010.) Free software focuses on the fundamental freedoms it gives to users, whereas open source software focuses on the perceived strengths of its peer-to-peer development model.[2] FOSS is a term that can be used without particular bias towards either political approach.

^Gallant, John (1985-03-18). "IBM policy draws fire – Users say source code rules hamper change". Computerworld. Retrieved 2015-12-27. While IBM's policy of withholding source code for selected software products has already marked its second anniversary, users are only now beginning to cope with the impact of that decision. But whether or not the advent of object-code-only products has affected their day-to-day DP operations, some users remain angry about IBM's decision. Announced in February 1983, IBM's object-code-only policy has been applied to a growing list of Big Blue system software products

^Mark (2008-05-08). "The Curse of Open Source License Proliferation". socializedsoftware.com. Retrieved 2015-11-30. Currently the decision to move from GPL v2 to GPL v3 is being hotly debated by many open source projects. According to Palamida, a provider of IP compliance software, there have been roughly 2489 open source projects that have moved from GPL v2 to later versions.

^Torvalds, Linus. "COPYING". kernel.org. Retrieved 13 August 2013. Also note that the only valid version of the GPL as far as the kernel is concerned is _this_ particular version of the license (ie v2, not v2.2 or v3.x or whatever), unless explicitly otherwise stated.

^Kerner, Sean Michael (2008-01-08). "Torvalds Still Keen On GPLv2". internetnews.com. Retrieved 2015-02-12. "In some ways, Linux was the project that really made the split clear between what the FSF is pushing which is very different from what open source and Linux has always been about, which is more of a technical superiority instead of a -- this religious belief in freedom," Torvalds told Zemlin. So, the GPL Version 3 reflects the FSF's goals and the GPL Version 2 pretty closely matches what I think a license should do and so right now, Version 2 is where the kernel is."

^corbet (2006-10-01). "Busy busy busybox". lwn.net. Retrieved 2015-11-21. Since BusyBox can be found in so many embedded systems, it finds itself at the core of the GPLv3 anti-DRM debate. [...]The real outcomes, however, are this: BusyBox will be GPLv2 only starting with the next release. It is generally accepted that stripping out the "or any later version" is legally defensible, and that the merging of other GPLv2-only code will force that issue in any case

^Prokoudine, Alexandre (26 January 2012). "What's up with DWG adoption in free software?". libregraphicsworld.org. Archived from the original on 2016-11-09. Retrieved 2015-12-05. [Blender's Toni Roosendaal:] "Blender is also still "GPLv2 or later". For the time being we stick to that, moving to GPL 3 has no evident benefits I know of."

^Denis-Courmont, Rémi. "VLC media player to remain under GNU GPL version 2". videolan.org. Retrieved 2015-11-21. In 2001, VLC was released under the OSI-approved GNU General Public version 2, with the commonly-offered option to use "any later version" thereof (though there was not any such later version at the time). Following the release by the Free Software Foundation (FSF) of the new version 3 of its GNU General Public License (GPL) on the 29th of June 2007, contributors to the VLC media player, and other software projects hosted at videolan.org, debated the possibility of updating the licensing terms for future version of the VLC media player and other hosted projects, to version 3 of the GPL. [...] There is strong concern that these new additional requirements might not match the industrial and economic reality of our time, especially in the market of consumer electronics. It is our belief that changing our licensing terms to GPL version 3 would currently not be in the best interest of our community as a whole. Consequently, we plan to keep distributing future versions of VLC media player under the terms of the GPL version 2.